Electrochemical characterization of copper chemical mechanical polishing in l-glutamic acid–hydrogen peroxide-based slurries

The effect of l-glutamic acid as complexing agent in the presence of hydrogen peroxide as oxidizer in copper chemical mechanical polishing (CMP) slurry is investigated. In the CMP process, the work surface is moved against a pad, with slurry flowing between the surface and the pad. The polish rate was found to be stable over a wide range of hydrogen peroxide concentration. High concentration of either l-glutamic acid or hydrogen peroxide leads to a reduction in polish rate, but a high concentration of both chemicals does not reduce the polish rate. In the absence of hydrogen peroxide, the Cu polish rate was 0 for all the l-glutamic acid concentrations investigated. However, potentiodynamic polarization curves do not show any sign of passivation when l-glutamic acid was present in the solution. In situ open circuit potential measurements show that copper redox reactions as well as hydrogen peroxide redox reactions contribute in determining the electrochemical behavior. We propose that l-glutamic acid inhibits the copper dissolution by adsorption onto the metallic copper, but enhances copper dissolution by complexing copper ions. The results show that it is possible to conduct controllable copper CMP in mildly acidic slurries with hydrogen peroxide as oxidizer and l-glutamic acid as complexing agent.     

Oxidation with manganate solutions

Summary The reaction between Tl⁺ solutions and manganate is sluggish. In the titration of Tl⁺ with manganate solution the end points are always attained earlier than the theoretical. When the reaction is accelerated by NaCl and heating to 45–50° C the end points were found to be concordant with the theoretical values. Titration of manganate with Tl⁺ solutions gives accurate results in presence of telluric acid but not in its absence. It is also possible to determine Tl⁺ by oxidation with an excess of K₂MnO₄ using arsenite as a back titrant for excess oxidant.Part III: Issa, I. M., and M. G. E. Allam: Z. analyt. Chem. 175, 103 (1960).     

Oxidations with potassium permanganate in the presence of fluoride

Summary Quadrivalent selenium can be determined with fair accuracy by mixing with an excess of KMnO₄ in the presence of 25–75 ml of 2% NaF solution and 4–7 ml of 9 N sulfuric acid. After leaving the reaction mixture for 10–30 minutes the excess KMnO₄ is estimated by one of the following procedures: A) Titration of the excess KMnO₄ with monovalent mercury, B) Adding an excess of Hg₂ ²⁺ solution to react with the excess KMnO₄ followed by titrating the excess mercurous with KMnO₄ solution.Part I: Issa, I. M., and M. Hamdy, Z. analyt. Chem. 172, 94 (1980).     

Polarography of Solochrome Violet RS-Metal Complexes at High pH

Zusammenfassung Weitere Studien über die Magnesium-Solochrome Violett RS-Reaktion werden mitgeteilt. Es wird gezeigt, daß das pH-Optimum für die Polarographie bei 11,5 liegt. In Anwesenheit von Calcium versagt die Bestimmung bei diesem pH. Der Einfluß von Calcium auf die Polarographie von Magnesium wird beschrieben und Möglichkeiten der Eliminierung der Calciumstörung untersucht. Als geeignet wird die Entfernung von Calcium als Oxalat gefunden und eine Arbeitsvorschrift wird angegeben. Die Methoden werden diskutiert.

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Summary Further studies of the magnesium-solochrome violet RS reaction are presented. It is shown that the optimum pH for polarography is about 11.5, but that this value falls when calcium is present. The effect of calcium on the polarography of magnesium is described and means of eliminating calcium interference considered. The removal of calcium by precipitation with ammonium oxalate is described and a satisfactory procedure is developed. Certain aspects of the method are discussed and the possible scope is mentioned.

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Part I see Palmer, S. M., and G. F. Reynolds ¹.     

Solochrome Violett R. S. as a new colorimetric reagent

Summary The reaction between molybdenum and the sulphonic acid azo dye Solochrome Violet R.S. has proved to be a suitable one for the microdetermination of Mo amounts covering the range of 0.3 to 10 ppm in purely aqueous solutions. The variation of extinction with concentration conforms satisfactorily with Beer's law throughout the whole range. Very many cations and anions do not interfere with such a determination. Ferric iron up to 2 mg per 25 ml is completely masked with ascorbic acid.Part II: Khalifa, H., and S. W. Bishara: Z. analyt. Chem. 178, 345 (1960).     

Phosphorylation Products of Poly-dl(l)-serine

Two phosphorylation products of polyserine are described. The first product was obtained by coupling poly-dl-serine with benzyl phosphoric acid, in the presence of dicyclohexyldiimide, and subsequent debenzylation with anhydrous HBr. The second product was obtained by the phosphorylation of poly-dl-(orl)-serine with chlorophosphoric acid.The peptide derivative (IV), obtained via a benzyl phosphate intermediate, was shown to consist of approximately equimolar amounts of seryl and O-phosphoseryl residues. All of the phosphorous in this polyserine derivative is bound to the hydroxyl groups of the seryl residues and appears in the form of phosphoric acid monoester.The phosphorylation of poly-dl-(orl)-serine with chlorophosphoric acid yielded a derivate (VI) containing one phosphate group per each serine residue. An extensive rearrangement of the polypeptide chain occured during the phosphorylation reaction with chlororophosphoric acid as a result of an N to O acyl shift. Approximately 80 percent of the phosphate groups of VI are linked to the -amino groups of the polyester-polyamide VI, the remaining 20% of the phosphates are linked to the -hydroxyl groups of the modified peptide.With 2 FiguresDedicated to Prof. Dr.F. Wessely on the occasion of his 70th birthday.     

Die chemische Analyse durch Hochfreqnenzmethoden

Ohne Zusammenfassung Blaedel, W. J., T. S. Burkhalter, D. G. Flom, G. Hare und F. W. Jensen: Analyt. Chemistry : 4, 198 (1952). Digest of round-table discussion at 119. Meeting, Amer. Chem. Soc., Div. of Anal. Chem., Cleveland, Ohio.